After years of resistance, Major League Baseball decided last winter to expand the use of video replays on disputed calls. Important matters like games and championships can turn on whether umpires get it right. So why haven't police throughout the country made a priority of putting video to work in their jobs? The stakes, after all, are much higher: even life and death.

The fatal shooting of 18-year-old Michael Brown by Office Darren Wilson in Ferguson, Mo., is a classic example of how vital such recordings can be. The police say Brown attacked Wilson and tried to grab his service pistol and was shot in the ensuing struggle. Dorian Johnson, who was with Brown, said Wilson attacked his friend, shot him in the chest and, when Brown tried to flee, shot him in the back.

An autopsy revealed six wounds — none in Brown's back, though one assistant in the autopsy said a shot in Brown's arm might have come from behind. The autopsy showed no evidence of a struggle. Tests on Brown's clothing should reveal whether he was shot at close range. But all this is an attempt to reconstruct an event from memory and remnants. It would be far easier to establish what happened had Officer Wilson been equipped with a video device that recorded the encounter.

Many police departments have installed video recorders on squad car dashboards, and some have gone further by adopting body cams that provide hours of color footage. More than 1,000 departments now use the latter devices. The Chicago Police Department has dashboard cams in 700 of its 1,280 cars, but it hasn't adopted body cams.

Last year, in ruling that New York City police had violated constitutional rights with their use of stop-and-frisk, a federal court ordered the department to equip cops in several precincts with body cameras. Judge Shira Scheindlin surmised that their use would "alleviate some of the mistrust that has developed between the police and the black and Hispanic communities" and would be "helpful to members of the NYPD who are wrongly accused of inappropriate behavior."

Experience supports her. When the California city of Rialto adopted gadgets that could be attached to an officer's sunglasses or collar, it found that complaints against cops plunged by 88 percent and police use of force fell by 59 percent. Chief William Farrar told The New York Times, "When you put a camera on a police officer, they tend to behave a little better, follow the rules a little better. And if a citizen knows the officer is wearing a camera, chances are the citizen will behave a little better."

Some police and citizens, of course, behave badly anyway. In those cases, the footage makes it far easier to establish fault and punish the wrongdoer.

The devices aren't cheap. Those in use in Rialto cost about $900 apiece. Taser International has a model advertised for $399. For New York, the cost of equipping all officers could be up to $31 million.

But as the Public Advocate of New York noted in a report, the city paid $152 million in compensation for alleged police misconduct. The cameras would "reduce the money the city spends on lawsuits resulting from police misconduct," it concluded.

The Better Government Association has calculated that Chicago spent $521 million over the last decade in settlements, judgments and legal fees stemming from police misconduct cases.

Rules are needed to make sure citizen privacy is protected, while assuring that unscrupulous cops can't alter or delete unflattering images. But those requirements shouldn't be hard to meet.

Had these devices been in use in Ferguson, they could have saved everyone a lot of trouble and confusion trying to figure out exactly what happened that led to the death of Michael Brown. They might even have served to keep him alive.

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